Semi-inclusive polarized DIS in terms of Melin moments.I. Light sea quark polarized distribustions

In connection with the semi-inclusive polarized DIS, it is proposed to consider the first Melin moments $\Delta q$ of the polarized quark and antiquark densities, instead of the respective variables $\delta q(x)$, local in Bjorken x themselves. This gives rise to a very essential simplification of the next to leading order (NLO) QCD and, besides, allows one to use the respective QCD sum rules. An expression for $\Delta\bar{u}-\Delta\bar{d}$ in NLO is obtained which is just a simple combination of the directly measured asymmetries and of the quantities taken from the unpolarized data.